Nisus Writer Express is superb. There, I've said the most important part of the review.
You want more details, you greedy MacUpdate reader, don't you? Well, let's start with NWE's greatest strength: its interface. Besides being very pretty, the NWE work interface is the most elegantly functional I've ever used in a word processor. The Tool Drawer is amazing. It holds all sorts of sweet tools, everything from your styles to a [b]live thesaurus[b] (yeah, a thesaurus that quietly offers possible synonyms for what you've just typed, and yes, it's amazing). The drawer is highly customizable, in the most Mac-liscious, drag-and-drop sort of way. Create a drawer palette group that holds what [i]you[/i] need.
I'm an interface junkie, so it's very important to me that my workspace works with me. A custom palette group goes nicely with my enlarged Draft View, no toolbar. In this mode I can writewritewrite and get everything down, no extra crap getting in the way. Then I can switch to Page View and change palette groups to do the final formatting and whatnot.
Text renders beautifully in NWE. Unlike Word, NWE makes full use of Mac OS X's Cocoa objects, which have wonderful text display features. The Nisus folks have extended the standard objects to include such important features as right-to-left input and more customization of display.
Let's talk about some of the new features in 2.5. There's now automatic list editing, which works very nicely and is unobtrusive, so you don't find yourself suddenly and accidentally composing a list (unlike a particular program I despise *cough* Word). It's also very nicely customizable.
The Nisus people have created a new technology, in partnership with such venerable small software companies as The Omni Group and many others, called LinkBack. Basically, any LinkBack-aware application can paste in content from any other LinkBack-aware app. Then, when you double-click that content, it opens it in the original program for editing. Try this with NWE and the newest version of OmniGraffle. Whoa. Or Keynote (if you download a plugin). It's pretty cool. Developers can freely add LinkBack capabilities to their apps, and it's not particularly difficult. We'll be seeing more and more programs supporting this, particularly those from smaller companies who want to provide the best user experience and usefulness possible.
NWE's implementation of style sheets has always been strong, but the revamped style editor is even more fantastic. It very clearly organizes your character, paragraph, and list styles, then shows you what attributes each style has. Unfortunately, NWE can't yet export/import style sheets, so you'll either have to put the right styles in your templates or create them in each document you use (assuming you're using custom styles and not just the standard ones). This isn't a huge deal, by any means, but it would be nice.
This new version seems very stable to me so far. No crashes, no glitches, nothing out of the ordinary. I'm happy.
I could keep going about the many reasons I love using Nisus Writer Express (I am a writer, after all), but I really just recommend you download and try it yourself.